The present invention relates to a method and an apparatus for joining plate materials made of aluminum alloy or pressed materials.
In conventional joining technique, plate materials or materials pressed in advance in a three dimensional shape are superposed to be joined by electric resistance welding, arch welding, adhesives, bolt tightening or rivets.
When the materials are in the complex three dimensional shape, spot welding is used which can locally join a plurality of scattered joining portions.
Another joining technique is disclosed in Japanese Patent No. 2712838 which is a joining method by frictional agitation in a non-melting condition. This joining technique is such that a projection called a probe is rotatably inserted and translated in a joining surface of butted two members to plasticize metal texture near the joining surface by frictional heat and to thereby effect joining.
In the above spot welding, an optimal welding condition is selected to be set depending upon each welding portion when the materials are in the complex three dimensional shape or have different thickness or quality. This requires a large transformer and voltage source for applying high voltage on a welding electrode, and a circulating system of a cooling medium for cooling the transformer, involving immense investment in equipment.
In the joining technique disclosed in the above patent, the probe is inserted in the surfaces of the metal members to be moved so that welding marks (holes) from which the probe is pulled out are left at starting and ending points on a moving trace of the probe. This causes a problem in appearance that the technique cannot be used for areas where the welding marks are in sight and requires forming in advance a pad so as to remove the welding marks in post treatment and setting the starting and ending points of the probe on the pads.
The present invention is made in view of the above problems and its object is to provide a method and an apparatus for joining which requires small investment in equipment and can firmly join materials without leaving joining marks.
In order to solve the above problems and achieve the above object, according to first to third, eighth and ninth aspects of the present invention, moving frictional agitating means having a projection at an end portion thereof and rotating around an axis thereof to scattered joining portions, and joining the materials by pressing the projection on the joining portion permit joining materials which is press formed in advance in a three dimensional shape and cannot effect continuous joining with small investment in equipment without leaving welding marks.
According to fourth aspect of the present invention, rotating said frictional agitating means to press the end portion thereof on the joining portion, inserting the projection in the materials and agitating the materials by friction in a non-melting condition to join the materials permits joining with heat distortion restrained.
According to fifth and eleventh aspects of the present invention, a receiving member is provided opposite the frictional agitating means such as to grip the materials with the agitating means, and the agitating means and receiving member are mounted to an end of an arm of a multiarticulated robot movably in three dimensions, whereby the plurality of scattered joining portions can be locally joined even when the materials are in the complex three dimensional shape.
According to sixth aspect of the present invention, the projection is extensibly provided so that satisfactory joining can be achieved even when total thickness is large and when many materials are superposed.
According to seventh aspect of the present invention, the frictional agitating means is arranged opposite each other with the materials therebetween and grips the materials by tips of the mutually opposed frictional agitating means to be pressed, whereby joining time can be shortened and whereby satisfactory joining can be achieved even when the total thickness is large or many materials are superposed.
According to tenth aspect of the present invention, rotating the frictional agitation means to press on the end portion thereof on the superposed materials, inserting the projection in the materials and agitating the materials by friction in the non-melting condition to join the materials permits joining with the heat distortion restrained.
According to twelfth aspect of the present invention, pressing the frictional agitating means from a thinner side of the superposed materials permits joining with high capability of agitation even when the materials have different thickness.